Impact of Winds from Intermediate-Mass Stars on Molecular Cloud Structure and Turbulence

TL;DR

This study uses magnetohydrodynamic simulations to investigate how winds from intermediate-mass stars influence molecular cloud structure and turbulence, revealing that observed features imply higher mass-loss rates than standard models predict.

Contribution

The paper demonstrates that stellar winds significantly affect cloud morphology and turbulence, and suggests that actual stellar mass-loss rates are much higher than theoretical predictions.

Findings

Winds impact the Fourier velocity spectrum of clouds.

Density and velocity distributions indicate wind presence.

Mass-loss rates are inferred to be >10^{-7} Msun/yr, higher than models suggest.

Abstract

Observations of nearby molecular clouds detect "shells", which are likely caused by winds from young main sequence stars. However, the progenitors of these observed features are not well characterized and the mass-loss rates inferred from the gas kinematics are several orders of magnitude greater than those predicted by atomic line-driven stellar wind models. We use magnetohydrodynamic simulations to model winds launching within turbulent molecular clouds and explore the impact of wind properties on cloud morphology and turbulence. We find that winds do not produce clear features in turbulent statistics such as the Fourier spectra of density and momentum but do impact the Fourier velocity spectrum. The density and velocity distribution functions, especially as probed by CO spectral lines, strongly indicate the presence and influence of winds. We show that stellar mass-loss rates for individual stars must be $\dot m_w \gtrsim 10^{-7}$ Msun yr$^{-1}$, similar to those estimated from observations, to reproduce shell properties. Consequently, we conclude that B and A-type main sequence stars have mass-loss rates several orders of magnitude larger that those predicted by models or that young stars are more variable than expected due to magnetic activity or accretion.